Field of the Invention
The present invention relates to a droplet ejecting apparatus and a droplet ejecting method which use pressure generating elements to eject droplets.
Description of the Background Art
A droplet ejecting apparatus which varies the pressure in a plurality of pressure chambers filled with a liquid by means of pressure generating elements to thereby eject the liquid filling the pressure chambers from nozzles in the form of droplets has been hitherto employed (as disclosed in Japanese Patent Application Laid-Open No. 2012-161917, for example).
In the droplet ejecting apparatus (droplet jetting apparatus) disclosed in Japanese Patent Application Laid-Open No. 2012-161917, an ejecting head (recording head) includes the plurality of pressure chambers and the plurality of nozzles provided in the respective pressure chambers. Ink in the pressure chambers is jetted out of the nozzles by the deformation of piezoelectric elements provided in the respective pressure chambers. The ejecting head further includes a liquid filling chamber (reservoir) in communication with the pressure chambers and serving as a supply path for supplying the ink from an ink supply source to the respective pressure chambers (paragraph 0025 and FIG. 3).
When such an ejecting head ejects a liquid containing precipitable ingredients after a prolonged pause, the precipitable ingredients are prone to precipitate in the liquid filling chamber and in the pressure chambers. The precipitation of the precipitable ingredients in the liquid filling chamber might give rise to a problem such that liquid flow passages near communication ports which provide communication between the liquid filling chamber and the pressure chambers are narrowed down by the precipitable ingredients.
To solve the problem of the precipitation in the pressure chambers, what is called spitting and flushing have been hitherto performed. In the spitting and flushing, ink is in general ejected from all of the nozzles in unison by the same ejection method as a normal ejecting operation. This causes the ejection of precipitated parts in the pressure chambers from the nozzles to eliminate the accumulation of the precipitable ingredients in the pressure chambers.
In the conventional spitting and flushing, liquid flows directed from the liquid filling chamber toward the pressure chambers are produced in the liquid filling chamber, but are not sufficient to eliminate the precipitation in the liquid filling chamber. To solve the problem of the precipitation in the liquid filling chamber, what is called a purge has been performed which causes a large amount of ink to be ejected by the application of an external force to the ejecting head.
Unfortunately, the purge consumes a greater amount of ink than the spitting and flushing. Also, the purge requires a greater number of steps than the spitting and flushing because the cleaning of the ejecting head is necessary after the purge. It is hence desirable that the precipitation in the liquid filling chamber is eliminated by what is called the spitting and flushing without the use of the purge.